Dirk Kuyt played as the lone central striker with Steven Gerrard, playing his 500th game for the Reds, in a supporting role.
Not one serious chance was created in the opening half, Liverpool not having enough up front to make things happen.
Rovers striker Franco Di Santo should have scored a minute into the second period but was painfully slow to get the ball under control and was dispossessed by Daniel Agger.
Gerrard tested Paul Robinson from 25 yards but sub Ngog wasted the best chance of the game on 71 when he turned Glen Johnson’s right-wing cross against the crossbar, with Dirk Kuyt’s follow-up deflected wide.
Benni McCarthy dragged a late shot wide but the game petered out after that.